meristems of Ferns as a Phylogenetic Study. 309 
typical apex of the root of Hymenophyllaceae is coincident in 
structure with that of other leptosporangiate Ferns. 
The apex of the root has been investigated in a large 
number of other leptosporangiate Ferns : e. g. by Naegeli 
and Leitgeb (1. c.) in Asplenium Filix-foemina , P ter is aquilina 
and hastata , Platy cerium alcicorne , Blechnum Occident ale ; by 
Hofmeister in Aspidium Filix-mas 1 ; by Hanstein in Marsilia 2 ; 
by Strasburger in Pteris cretica z , and in Azolla 4 , etc., etc. I 
have also myself investigated the apices of roots of Cyathea 
insignis , Eat., Gleichenia circinata , Sw., 67. fiabellata , R. Br., 
6/. rupestris , Lygodium scandens , Aneimia hirta, and Phyl- 
litidis, and Pilularia globulifera. It will be seen that among 
the plants above noted there are representatives of all the 
families of leptosporangiate Ferns, including the Hydropteri- 
deae : in all of them the organic apex of the root conforms 
in structure to the type laid down by Naegeli and Leitgeb : 
all have a single, three-sided, pyramidal apical cell, from the 
sides of which segments are cut off in regular succession 
by walls parallel to the three sides, and these are forma- 
tive of the body of the root : after each series of three such 
segments a fourth is cut off from the base of the pyramidal 
cell, and such segments are formative of the root-cap. 
This type of construction has been represented diagram- 
matically by Sachs 5 in a figure which is here reproduced 
(Fig. 1 ): in this it is to be noted that the centre of con- 
struction (6) of the whole system of curves lies within the 
apical cell itself, and that the whole (exclusive of the root-cap) 
falls under that series of systems of construction which are 
designated as confocal* : there may be slight variations in 
detail of the succession of the segmentations ; thus Kny notes 
1 Higher Cryptogamia, Ray Soc. Plate XXVI. 
2 Pringsh. Jahrb. IV, p. 230. 3 Practicum, p. 278. 
4 Ueber Azolla, p. 45. 
5 Arbeiten d. Bob Inst. Wiirzb. Bd. II, Taf. IV, Fig. 12. 
6 Compare Sachs’ Lectures, Clarendon Press, 1887, P- 45 1 - The term ‘ confocal ’ 
applies properly to the body of the root only, the root-cap being coaxial : but still 
this type may for brevity be termed confocal to distinguish it from that in which 
the construction of the body of the root is coaxial. 
